Prestressed concrete reinforcing arch structure



April 23, 1968 A. v.- BROQUIST 3,378,965

` PRESTRESSED CONCRETE REINFORCING ARCH STRUCTURE -Filed OC'L. 18, 1965INVENTOR.

ALBEN V. BROQUIST ATTORNEYS United States Patent O 3,378,965 PRESTRESSEDCNCRETE REINFORCING ARCH STRUCTURE Alben V. Broquist, Chisago City,Minn. 55013 Filed oei. is, 196s, ser. No. 496,864 3 Crarms. (el. s2s8ABSTRACT F THE DISCLOSURE A reinforced concrete arch structure having aprestressed core imbedded in the concrete and Acomprising a number ofsections consisting of parts adapted to he assembled in the field and tohe pre-stressed during or after erection.

The herein disclosed invention relates to concrete reinforcingstructures and has for an object to provide a prestressed reinforcingstructure having both a compression member and a number of tensionmembers.

Another object of the invention resides in providing a structure whichmay be stressed in the field or during its fabrication.

A still further object of the invention resides in providing stressingmeans forming a part of the reinforcing structure and embedded with thesame in the concrete.

A feature of the invention resides in constructing the compressionmember in sections of ceramic or similar material and preferably hollowand in the form of a tube with the ends of adjacent sections a-buttingone another.

Another object of the invention resides in providing a construction bymeans of which a number of reinforcing structures may be arranged in theform of an arc of a circle whereby the reinforcing members may be usedin arches.

An object of the invention resides in Iproviding plates bearing againstthe ends of the compression member and with the tension membersextending through the plates and threaded to receive nuts which whentightened up, stress the reinforcing structure.

Other objects of the invention reside in the novel combination andarrangement of parts and in the details of construction hereinafterillustrated and/or described.

In the drawings:

FIG. 1 is a perspective view of a concrete reinforcing structureillustrating an embodiment of the invention.

FIG. 2 is a longitudinal sectional view of ya beam or joist in which areinforcing structure similar to that shown in FIG. 1 has been employedand taken on line 2 2 of FIG. 3.

FIG. 3 is a cross sectional view taken on line 3 3 of FIG. 2.

FIG. 4 is a view similar to FIG. 2 showing a section of an arch with anumber of reinforcing structures arranged in the form of an arc.

FIG. 5 is a sectional view taken on line 5 5 of FIG. 4 and drawn to agreater scale.

FIG. 6 is a plan sectional view of the stressing means shown in FIG. 5and taken on line 6 6 of FIG. 5.

FIG. 7 is a fragmentary of a modi-cation of the reinforcing structureshown in FIGS. 4, 5, `and 6.

In the construction of pre-stressed reinforced concrete construction thecommon practice has been to pre-stress the tension members while theywere erected in the forms and to cast the concrete about the same whileso held. This requires rather complicated and heavy machinery and slowsdown the process of casting the concrete building -components in whichthe reinforcing structures are used. With applicants invention thereinforcing structure is pre-stressed before insertion in the forms withthe stressing means forming part thereof.

ICC

Applicants reinforcing structure las used in beams and joists is bestshown in FIGS. 1, 2, and 3 and comprises a compression member 10 and aplurality of tension members 20. Cooperating therewith is stressingmeans 30 and which is disposed at the ends of the compression member 10.

The compression member 10 consists of a number of sections 11 which aretubular in form and which have tubular walls 12 with a bore 13 therein.These sections have ends 14 and 15 which abut each other and which takenin their entirety form the elongated compression member 10. The sections11 of the compression member 1t) are preferably constructed of anon-ferrous material such as a ceramic material or of con-crete.Ordinary sewer tile have been found suitable for the purpose.

The tension members consist of rods formed of metal and which have ends21 extending outwardly beyond the ends 14 and 15 of the end sections 16and 17 of compression member 10.

The stressing means of the reinforcing structure includes two caps orplates 31 and 32 which are constructed of metal and which butt upagainst the ends 14 and 15 of the last sections 16 and 17 of thecompression member 10. These plates have holes 33 drilled in the sameand through which the ends 21 of the rods 20 extend. These ends arethreaded to receive nuts 34 which bear against the outer surface 35 ofthe plates 31 and 32.

By tightening up the nuts 34 on the ends of the rods 20, the compressionmember 10 is placed in compression and the tension members 20 arestressed in tension. Thus a pre-stressed concrete reinforcing structureis provided which may be inserted into the forms for the concretebuilding components prior to the casting of the same.

For the purpose of illustrating the application of the invention aportion of a building component has been shown in FIGS. 2 and 3. Thiscomponent may be used in 4constructing a floor or a roof. This componentis elongated in form having sides 41 and 42, ends 43 and 44, a top 45and a bottom 46. The pre-stressed reinforcing member is imbedded in theconcrete 47 forming said component with the entire reinforcing membercovered with concrete. The same may if desired be placed nearer thebottom 46 to bring more of the upper portion of the component incompression. In the sides 41 of the component are formed grooves 48 andon the sides 42 are tongues 49. The tongue 49 of one component ts intothe groove 48 of the adjacent component to lock the parts together andprovide an interlock between the various components and an unitaryIconstruction.

In FIGS. 4, 5, and 6 the reinforcing structure indicated by thereference numeral 50 has been shown as applied to an arch. Instead of along straight reinforcing structure, several short units are employed,which are connected together to form a composite structure arcuate inform. Four of the units of this structure have been shown in FIG. 4 anddesignated by the reference numerals Si, 52, 53, and 54. Each of theseunits consists of a -compression member formed with three tubularsections 56, 57, and 58. These units also have tension members, theunits 51 and 53 having tension members 61, 62, and 63 and the units 52and 54 having tension members 64, 65, and 66. Each unit has threetension members, and the tension members of one unit are interposedbetween those of the other unit, so that the members are sixty degreesapart. If desired, however, the tension members of one unit may beplaced closer to those of the adjoining unit.

The stressing means of the reinforcing structure 50 consist of plates 67and 68 for each section having holes through which the tension members61, 62, 63, 64, 65, and 66 and nuts 69 screwed on the threaded ends ofthe tension members extend, the same as with the other form of theinvention. Due to the curvature of the completed reinforcing structurethe plates 67 and 68 of adjoining units become spaced at the convexportion of the ar-ch and contact one another at the concave portion ofthe arch. In order to transmit stresses from one unit to the other, thetwo adjoining caps between the units are made integral with a connectingportion 71 therebetween. The parts may be welded together or a singleplate ernployed, bent at 72 and 73 to form the connecting portion 71 andwith the opposite edges contacting and welded together. If desired thecomposite structure may be cast from malleable iron or similar material.

Opposite the nuts 69 and in the plates Opposite the plates engaged bythe nuts 69 are openings 74, and through which a wrench may be insertedto engage the nuts and manipulate the same.

Concrete indicated at 76 is poured into the forms in which thereinforcing structure is positioned to form building components similarto those previously described.

In FIG. 7 is shown a modification of the reinforcing structure for usein arches. This structure is similar to the foregoing structure, and thesame reference numerals will be used to designate like parts. The plates67 and 68 are the same except the connecting portion 7l is dispensedwith. Also holes 75 have been substituted for the openings 74. In thisform of the invention the tension members extend through both of theplates 67 and 68. These members, between the plates 67 and 68 havesleeves '77 mounted on them and which form spacers serving the samepurpose as the conne-cting portion 71 of the other form of theinvention. Beveled washers 78 underlying the nuts 69 provide a squareseat for said nuts.

The method of using the invention is obvious. The parts can be assembledat the factory and shipped in an erected form or the parts can beerected at the site where the reinforcing structure is to be used. Ineither case a trough is provided of the desired length and thecompression member sections arranged in the trough in abutting relation.The end plates are then held in position while the tension members 20are threaded through the holes 53 in the end plates and the nuts 54applied. The nuts can then be tightened to give the desired initialstress.

The advantages of the invention are manifest. Heavy cumbersome equipmentfor the purpose of stressing the tension members is dispensed with andalso the supporting structure for temporary stressing the tensilemembers is done away with. By the use of hollow tubes for thecompression members less concrete is employed than would otherwise benecessary. The reinforcing structure i may be rapidly assembled andstressed and when placed in the forms, may be completely covered withconcrete to form the ultimate building component.

Changes in the specific form of the invention, as herein described, may`be made within the scope of what is claimed without departing from thespirit of the invention.

Having described the invention, what is claimed as new and desired to heprotected by Letters Patent is:

1. In a reinforced concrete arch structure having a prestressed coreimbedded in the concrete, said core comprising a number of sections cachhaving:

(a) an elongated compression member,

(b) a plurality of elongated rods, threaded at their ends and disposedabout the compression member,

(c) end plates at the ends of the compression member and against whichthe compression members bear,

(d) said rods extending through said plates,

(e) nuts on said rods engaging said plates to compress the compressionmember and tension the rods,

(f) the plates at the adjoining ends of the sections being arranged inV-shaped formation and (g) connecting members between the adjoiningplates for holding the plates in fixed relation.

2. A reinforced concrete arch structure according to claim 1 in which:

(a) at least one of the connecting members is integral with bothadjoining end plates.

3. A reinforced concrete arch structure according to claim 1 in which:

(a) at least one of the connecting members utilizes one of the rodswhich extends through both of the adjoining plates and (b) a sleeveencircling said red and engaging both of said plates.

References Cited UNITED STATES PATENTS 25,537 9/1855 Van Duzer 52-872,307,215 l/l943 Graef 52-86 X 2,874,812 2/1959 Clevett 52-86 X FOREIGNPATENTS 26,284 6/1923 France. 928,623 6/1947 France.

2,428 l0/l863 Great Britain. 452,126 1936 Great Britain. 511,262 1/1955Italy.

FRANK L. ABBOTT, Primary Examiner.

A. C. PERI-IAM, Examiner.

